Method of flameproofing acrylic fibers and the resulting product



Unite 3,186,868 METHOD OF FLAMEPROOFING ACRYLIC FIBERS AND THE RESULTING PRODUCT Julian J. I-Iirshfeld, Decatur, Ala., assignor, by mesne assignments, to Monsanto Company, a corporation of Delaware No Drawing. Filed Apr. 16, 1962, Ser. No. 187,927

. 21 Claims. (Cl. 117-136) This invention is concerned with rendering flameproof synthetic linear fibers. More specifically, this invention is concerned with rendering flameproof fibers composed of at least 80 percent acrylonitrile.

In the past the problem of flameproofing conventional textile materials has been well recognized. Many processes and techniques have been suggested as solutions to this problem, some of which have been highly successful. On the other hand, the new synthetic textile materials such as textiles containing acrylic fibers have received comparatively little attention. Now with the growth of the amount of synthetic fibers used today in the textile field, the problem has begun to receive .attention. One method has been suggested for rendering acrylic fibers flameproofed and that is to incorporate conventional flameproofing agents into the spinning dope during the extrusion of acrylic fibers into the spin bath, but the agents loose their eificiency because they are located too far from the periphery of the fibers or these agents impair many valuable characteristics of the fibers like the dyeability, resiliency, etc. In addition, it is known that inorganic acids retard the flame propagation of acrylic fibers. None of these acids however, stops the flame propagation.

The primary object of this invention is to produce a new composition of matterwhich includes the synthetic linear acrylic fibers which are flame proofed. Another of this invention is to provide a method for rendering the synthetic linear acrylic fibers flame proofed. Another object of this invention is to provide a method for rendering flameproof fibers composed of at least 80 percent acrylonitrile and up to 20 percent of another mono-olefinic monomer copolymerizable therewith. Another object of this invention is to provide a new composition of matter in which the fiber is composed of at least 80 percent acrylonitrile and up to 20 percent of another mono-olefinic copolymerizable monomer and flameproofing agents. Other objects of this invention will hereinafter become a part in the following detailed description and appended claims.

Generally the objects of this invention are obtained by treating the synthetic linear fibers with a solution of phytic acid and urea, phytic acid and urea and/ or formaldehyde. The fibers are then dried and then cured. It is not of importance how this solution of flameproofing agents is placed on the fabrics or fibers, as it may be applied by padding, immersion, spraying or any other conventional method of treating a fabric With a liquid.

More specifically, the synthetic linear fibers are treated with an aqueous solution of from 10 percent to 75 percent of phytic acid and from 5 percent to 50 percent of urea, with the preferred being 20 percent of phytic acid to 20 percent of urea. The fibers are then dried at a suitable temperature, for example from 150 F. to 220 F. and cured by heating to a temperature in the range of from 260 F. to 330 F. for a time period of from 4 minutes to 20 minutes with the preferred being heated to 280 F. for minutes. In addition to the above aqueous treat- 3,186,868 Patented June 1, 1965 ing solution, the synthetic linear fibers may also be treated with an aqueous solution containing from 10 percent to '75 percent of phytic acid, from 5 percent to 50 percent of urea and from 5 percent to 30 percent of formaldehyde with the preferred being 12.4 percent of phytic acid, 25 percent of urea and 25 percent of formaldehyde. The treated fibers are then dried at a temperature in the range of from 150 F. to 220 F. and then cured for 4 minutes to 20 minutes at 260 F. to 330 F. with the preferred being 280 F. to 10 minutes. In addition, an aqueous solution of from 10 percent to percent phytic acid and from 10 percent to 50 percent formaldehyde, with the preferred being 10 percent phytic acid to 20 percent formaldehyde may be used.

Although urea is especially useful and elfective in producing flameproofing characteristics on the synthetic linear acrylic fibers, other compounds closely related to same may be used, such as guanidine, dicyandiamide and other materials. In additionTother' compounds may be used instead of formalhedyde, such as acetaldehyde, glyoxal and sources of formaldehyde such as paraformaldehyde and trioxymethylene.

The polymeric materials, which may be employed in the practice of the present invention are polyacrylonitrile, copolymers, including binary and ternary polymers containing at least percent by weight of acrylonitrile in the polymer molecule, or a blend comprising polyacrylonitrile or copolymers comprising acrylonitrile with from 2 to 50 percent of another polymeric material the blend having an overall polymerized acrylonitrile content of at least 80 percent by weight. While the preferred polymers employed in the instant invention are those containing at least 80 percent of acrylonitrile, generally recognized as the fiber-forming acrylonitrile polymers, it will be understood that the invention is likewise applicable to polymers containing less than 80 percent acrylonitrile. The acrylonitrile polymers containing less than 80 percent acrylonitrile are useful in forming films, coating composi tions, molding operation and lacquers.

For example, the polymer may be a copolymer of from 80 to 98 percent acrylonitrile and from 2 to 20 percent of another monomer containing the @C linkage and copolymerizable with acrylonitrile. Suitable monoolefinic monomers, include acrylic, alpha-chloroacrylic and methacrylic acids; the acrylates, such as methylmethacrylate, ethylmethacrylate, butylmethacrylate, methoxylmethyl methacrylate, beta-chloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-l-bromo-ethylene; methacrylonitrile; acrylamide and methacrylamide; alpha-chloroacrylamide; or monoalkyl substitution products thereof; methylvinyl ketone; vinyl carboxylates, such as vinyl acetate, vinyl chloroacetate, vinyl propionate, and vinyl stearate; N-vinylimides, such as N-vinylphthalimide and N-vinylsuccinimide; methylene malonic esters; itaconic acid and itaconic esters; N-vinylcarbazole; vinyl furane; alkylvinyl esters; vinyl sulfonic acid; ethylene alpha, betadicarboxylic acids or their anhydrides or derivatives, such as diethylcitraconate, diethylmesaconate, styrene, vinyl naphthalene; vinyl-substituted tertiary heterocyclic amines, such as the vinylpyridines and alkyl-substituted vinylpyridines, for example, 2-vinylpyridine, 4-vinylpyridine, 2- methyl-S-vinylpyridine, etc.; l-vinylimidazole and alkylsubstituted l-vinylimidazole such as 2-, 4-, or 5-methyl-lvinylimidazole, and other C=C containing polymerizable materials.

The polymer may be a ternary or higher interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers, other than acrylonitrile, enumerated above. More specifically, and preferably the ternary polymer comprises acrylonitrile, methacrylonitrile and 2-vinylpyridine. The ternary polymer preferably contain from 80 to 98 per cent of acrylonitrile, from 1 to 10 percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18 percent of another substance such as methacrylonitrile or vinyl chloride.

The polymer may also be a blend of a polyacrylonitrile or of a binary interpolymer of from 80 to 99 percent acrylonitrile and from 1 to 20 percent of at least one other C=C containing substance with from 2 to 50 percent of the weight of the blend of a copolymer of from 10 to 70 percent of acrylonitrile and from 30 to 90 percent of at least one other C=C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of a copolymer of 90 to 98 percent acrylonitrile and from 2 to 10 percent of another mono-olefinic monomer, such as vinyl acetate, which is not receptive to dyestutf, with a sufficient amount of a copolymer of from 10 to 70 percent of acrylonitrile and from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine or l-vinylimidazole, to give a dyeable blend having an overall vinylsubstituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend.

The following examples are cited to illustrate the invention. They are not intended to limit it in any way. Unless otherwise noted, percentages as expressed in examples indicate percent by weight.

Example 1 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with an aqueous solution of 15 percent phytic acid and 15 percent urea and then dried at 220 F. for approximately 15 minutes and then cured for 8 minutes at 280 F. This tape was subjected to the AATCC Flammability Test Standard Test Method 33- 1957. The samples were extremely difficult to ignite and did not propagate flames.

Example 2 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 25 percent urea, 12.4 percent phytic acids and 25 percent formaldehyde and then dried at 220 F. for 15 minutes and then cured for 5 minutes at 320 F. This treated tape did not ignite even when being placed vertically above a burning gas burner.

Example 3 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl ace tate was padded with a solution of percent phytic acid and 20 percent formaldehyde and dried at 200 F. for minutes and then cured for 8 minutes at 280 F. This treated tape was then subjected to the same test as in Example 1 and the burning time of 3 samples resulted in a 30 second average versus seconds for an untreated sample.

Example 4 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of percent urea and 12.5 percent phytic acid and then dried at 200 F. for 15 minutes and then cured for 10 minutes at 280 F. This sample was subjected to the same test as in Example 1, but the sample would not ignite.

Example 5 A two inch wide tape of synthetic fabric composed of sample would not ignite at all.

fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 50 percent urea and 24 percent phytic acid and then dried at 200 F. for 15 minutes. This sample was then cured at 300 F. for 8 minutes. The sample was then subjected to the same flammability test as in Example 1, but it would not ignite. The hand of this sample remained commercially acceptable after being treated with the flameproofing agent.

Example 6 Example 7 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 50 percent urea and 24 percent phytic acid and then dried at 200 F. for 15 minutes. The sample was then cured at 280 F. for 10 minutes. The sample was tested as in Example 1, but the The hand remained of commercial acceptability.

Example 8 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 25 percent urea, 12.4 percent phytic acid and 25 percent formaldehyde and dried at 200 F. for 15 minutes. The sample was then cured at 280 F. for 10 minutes. The sample was then subjected to the same test as in Example 1, but the sample would not ignite at all.

Example 9 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 25 percent urea, 12.4 percent phytic acid and 25 percent formaldehyde and then dried at 200 F. for 15 minutes. The sample was then cured at 300 F. for 8 minutes. The sample was tested as in Example 1 but the sample would not ignite.

Example 10 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 25 percent urea, 12.4 percent phytic acid and 25 percent formaldehyde and then dried at 210 F. for 15 minutes. The sample was then cured at 320 F. for 5 minutes. The sample was tested as in Example 1, but the sample would not ignite. The color of the sample remained commercially acceptable along with the hand.

Example 11 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 20 percent urea and 20 percent phytic acid and dried at 220 F. for 15 minutes. The sample was then cured for 10 minutes at 300 F. The sample was then subjected to the same test as in Example 1, but it would not ignite.

Example 12 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 10 percent urea and 10 percent phytic acid and dried at 220 F. for 15 minutes.

The sample was then cured for minutes at 300 F. The sample was subjected to the same test as in Example 1, but the sample would not ignite.

Example 13 A two inch wide tape of synthetic fabric composed of fibers of 94 percent acrylonitrile and 6 percent vinyl acetate was padded with a solution of 10 percent phytic acid and 20 percent formaldehyde and dried at 220 F. for 15 minutes. The sample Was then cured for 8 minutes at 280 F. The sample was subjected to the same test, as in Example 1. The burning time of five samples treated as above resulted in a 30 second average versus 19 seconds for untreated samples.

Thus with the solutions of the present invention, it has been found that fabrics composed of acrylic fibers may be rendered flameproofed to a large degree, thus enabling the use of these fibers in many textile fields, such as clothing, rugs, etc.

It is understood that changes and variations may be made in the present invention by one skilled in the art without departing from the spirit and scope thereof, as defined in the appended claims.

I claim:

1. Flameproofed synthetic linear fibers comprising acrylic fibers treated with phytic acid and a member selected from the group consisting of lurea, formaldehyde and mixtures of same, said article being in dried form.

2. Flameproofed synthetic linear fibers composed of at least 80 percent acrylonitrile and up to 20 percent of another mono-olefinic copolymerizable monomer said fibers being treated with phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, said article being in dried form.

3. Flameproofed synthetic linear fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate, said fibers being treated with phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, said article being in dried form.

4. Flameproofed synthetic linear fibers composed of a blend of two copolymers, one copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine said fibers being treated with phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, said article being in dried form.

5. Flameproofed synthetic linear fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate, said fibers being treated with phytic acid and urea, said article being in dried form.

6. Flameproofed synthetic linear fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate, said fibers being treated with phytic acid and formaldehyde, said article being in dried form.

7. Flameproofed synthetic linear fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate, said fibers being treated with phytic acid, urea and formaldehyde, said article being in dried form.

8. Flameproofed synthetic linear fibers composed of a blend of two copolymers, one copolymer being 94 percent acrylonitrile and '6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, said fibers being treated with phytic acid and urea, said article being in dried form.

9. Flameproofed synthetic linear fibers composed of a blend of two copolymers, one copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, said fibers being treated with phytic acid and formaldehyde, said article being in dried form.

10. Flameproofed synthetic linear fibers composed of a blend of two copolymers, the first copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, said fibers being treated with phytic acid, formaldehyde and urea, said article being in dried form.

11. A method of flameproofing acrylic fibers which comprises treating said fibers with an aqueous solution of phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, drying the treated fibers and then curing the treated fibers.

12. A method of flameproofing fibers composed of at least percent acrylonitrile and up to 20 percent of another mono-olefinic copolymerizable monomer, comprising treating said fibers with an aqueous solution of phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, drying the treated fibers and then curing the treated fibers.

13. A method of flameproofing fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate comprising treating said fibers with an aqueous solution of phytic acid, and a member selected from the group consisting of urea, formaldehyde and mixtures of same, drying the treated fibers and then curing the treated fibers.

14. A method of flameproofing fibers composed of a blend of two copolymers, the first copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, comprising treating said fibers with an aqueous solution of phytic acid and a member selected from the group consisting of urea, formaldehyde and mixtures of same, drying the treated fibers and then curing the treated fibers.

15. A method of flameproofing fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate comprising treating said fibers with an aqueous solution of from 10 percent to 75 percent of phytic acid, 5 percent to 50 percent of urea and 5 percent to 30 percent of formaldehyde, drying the treated fibers and then curing the treated fibers.

16. A method of flameproofing fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate comprising treating said fibers with an aqueous solution of 20 percent phytic acid, 20 percent urea and 25 percent formaldehyde, drying the treated fibers and curing the treated fibers within a temperature range of from 260 F. to 330 F.

17. A method of flameproofing fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate comprising treating said fibers with an aqueous solution of 20 percent phytic acid and 20 percent urea, drying said fibers and curing said fibers in a temperature range of from 260 F. to 330 F.

18. A method of flameproofing fibers composed of 94 percent acrylonitrile and 6 percent vinyl acetate comprising treating said fibers with an aqueous solution of 10 percent phytic acid and 20 percent formaldehyde, drying the treated fibers and curing the treated fibers at a temperature of 280 F. for 10 minutes.

19. A method of flameproofing fibers composed of a blend of two copolymers, one copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, comprising treating said fibers with an aqueous solution of 20 percent phytic acid and 20 percent urea, drying the treated fibers and curing the treated fibers for 10 minutes at 280 F.

20. A method of flameproofing fibers composed of a blend of two copolymers, the first copolymer being 94 percent acrylonitrile and 6 percent vinyl acetate and the second copolymer being 50 percent acrylonitrile and 50 percent methylvinyl pyridine, comprising treating said fibers with an aqueous solution of 12.4 percent phytic acid, 25 percent urea and 25 percent formaldehyde, drying the treated fibers and curing the treated fibers for 10 minutes at a temperature of 280 F.

7 8 21. A method of flameproofing fibers composed of References Cited by the Examiner blend of two copolymers, the first copolymer being 94 UNITED STATES PATENTS percent acryionitrile and 6 percent vinyl acetate and the second oopolymer being 50 percent acrylonitrile and 50 $22 12 a1 n percent methylvinyl pyridine, comprising treating said 5 3047425 7/62 Hirshfeld'gt' ;I XR fibers with an aqueous solution of 10 percent phytic acid and 20 percent formaldehyde, drying the treated fibers WILLIAM MARTIN Primary Examine"- and curing the treated fibers for 10 minutes at 280 F. RICHARD D, NEVIUS, Examiner, 

11. A METHOD OF FLAMEPROOFING ACRYLIC FIBERS WHICH COMPRISES TREATING SAID FIBERS WITH AN AQUEOUS SOLUTION OF PHYTIC ACID AND A MEMBER SELECTED FROM THE GROUP CONSISTING OF UREA, FORMALDEHYDE AND MIXTURES OF SAME, DRYING THE TREATED FIBERS AND THEN CURING THE TREATED FIBERS. 